Even regular cars get to the point of renting being too expensive vs. buying. Quite regularly.
I've been using carnextdoor.com.au for years when ever my motorbikes weren't enough to get around.
But if you're renting a car even for 1-2 days a week, it quickly cost as much it would have had for running costs and purchasing a car outright. The numbers below are all AUD.
I'm about to pick up a new Ute (Dmax XTerrain) thats going to cost $238 per week over 5 years for finance. With running costs on top of that I'm budgeting for $400 per week.
That's a rental car for 1.5-2 days.
Carnextdoor and rentals made sense when I didn't need a car weekly, just monthly. The new Ute is relatively inexpensive to run (4 cylinder turbo diesel), it's big, big compared to cars from Europe, not big for the US I'm sure.
But for me it definitely made sense to get a 4x4 that services all my needs rather than a 4x4 and another small car.
Admittedly I go camping a lot so my needs are a little different. And I have dogs now so going camping on my motorbikes isn't much of an option now.